The veiled species of Hebeloma in the western United States / Alexander H. Smith, Vera Stucky Evenson, and Duane H. Mitchel.

The Subgenus Hebeloma

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Stipe 4-6 cm long, 2-3.5 mm thick, usually narrowed downward,
very fragile, readily splitting lengthwise, soon becoming dark rusty
brown from the base upward; surface with grayish pallid patches and
zoned from the broken veil, these remnants lutescent as stipe darkens,
the apex long remaining pallid and silky. FeSO4 on base of stipe dark
olive-brown, KOH on pileus cuticle dull olive-brown.
Spores 9-12 x 6-7 [xm, in profile obscurely bean-shaped to elliptic or ovate, in face view ovate to oblong; surface slightly punctate in
Melzer's reagent, wall not appreciably thickened, clay color in KOH,
not dextrinoid.
Hymenium.-Basidia 4-spored, 8-10 Ixm broad, containing numerous refractive "oil" droplets as revived in KOH. Pleurocystidia
none. Cheilocystidia variable: (1) fusoid-ventricose and 32-40 x 7-10
[Lm, apex obtuse; (2) cylindric to + clavate and 40-60 x 5-7 pxm, apex
obtuse; (3) cylindric or filamentous and flexuous, down to a basal
portion 7-11 JIm broad (but a few ventricose distal to the midportion),
not agglutinated.
Lamellar and pilear tissues.-Lamellar trama as revived in
Melzer's merely pale yellow but the subhymenium and hymenium
orange-red. Cuticle of pileus an ixolattice of tubular hyphae usually
having finely roughened walls, the hyphae 3-5 Ixm diam. Hypodermium hyphoid, dark rusty brown revived in KOH or Melzer's, the
hyphae with some wall thickenings and/or incrustations but these not
heavy or conspicuous. No dextrinoid debris noted in Melzer's mounts.
Pilear trama of + radial-interwoven hyphae with enlarged cells having
smooth walls. Clamp connections present.
Habit, habitat, and distribution.-Caespitose on wet earth under
spruce (P. engelmannii) above Elk Wallow, Fryingpan River, Pitkin
County, Colorado, August 29, 1979, Smith 90057 (type, Mich.)
Observations.-In many species of Hebeloma the stipe splits
lengthwise fairly readily, but in this species it is difficult to collect
specimens without having the stipe splitting into a number of segments. The veil is pallid but, as the stipe darkens, veil remnants in
contact with darkened areas slowly become dingy buff. The lack of
any distinctive odor or taste also aids in distinguishing this species. It
differs from H. subrimosum in the clustered habit of the fruiting
bodies, the more slender stipe, the nonrimose pileus, the strongly
brunnescent stipe, and the pileus being canescent and grayish brown
when faded.
5. Hebeloma ollaliense sp. nov.
Pileus 2-3 cm latus, obtusus demum late umbonatus vel convexus, ad marginem fibrillosus demum glaber, + alutaceus. Odor et